1. Field of the Invention
The present invention relates to an electronic component thickness measurement method, a method for manufacturing a series of electronic components using the measurement method, a series of electronic components manufactured by the manufacturing method, and an electronic component inspection apparatus, and particularly relates to a method for measuring the thickness of an electronic component mounted on a transparent plate, a method for manufacturing a series of electronic components using the measurement method, a series of electronic components manufactured by the manufacturing method, and an inspection apparatus for an electronic component mounted on a transparent plate.
2. Description of the Related Art
Japanese Patent Laying-Open No. 4-107000 discloses a configuration of an appearance classification apparatus for electronic components. In the appearance classification apparatus for electronic components that is disclosed in Japanese Patent Laying-Open No. 4-107000, components fed from a component feeder are spaced from each other on a continuously rotating transparent disk, a camera, which is disposed at a position that enables the camera to freely photograph the components on the transparent disk, photographs instantaneous images of the components, and the appearances of the components are inspected based on image signals derived from the instantaneous images. In the appearance classification apparatus for electronic components, the electronic components are classified, based on the results of the appearance inspection, by a classification mechanism provided at a certain position along a track of the components on the transparent disk.
In some cases, electronic components have to be classified by the appearance and the thickness. In the case where the appearance classification apparatus for electronic components that is disclosed in Japanese Patent Laying-Open No. 4-107000 is to measure the thickness of an electronic component via a camera, it is difficult to accurately measure the thickness of the electronic component due to the limitation in depth of field of the camera.
One method for precisely measuring the shape of an electronic component is the light section method. According to the light section method, light is applied to an electronic component from directly above the electronic component, the light reflected therefrom is received from which an image is obtained, and the shape of the electronic component is measured based on the image.
In the case where the thickness of an electronic component mounted on a transparent plate is to be measured via the light section method, the following method may be employed. Specifically, light is applied to the electronic component and the transparent plate, and the thickness of the electronic component is measured based on the distance between the position where the reflected light which is reflected from the upper surface of the electronic component is received and the position where the reflected light reflected from the upper surface of the transparent plate is received.
Regarding this method, however, the reflection coefficient of the applied light on the transparent plate is low and a part of the applied light causes multi-reflection in the transparent plate. Due to this, the position where the reflected light reflected from the upper surface of the transparent plate is received, which is used as a reference for measuring the thickness of the electronic component, is made unclear. It has therefore been difficult to measure via the light section method the thickness of an electronic component mounted on a transparent plate.